By Yereth Rosen
ANCHORAGE, Alaska (Reuters) - Preliminary tests appear to rule out radiation from Japan's tsunami-wrecked Fukushima nuclear power plant as the cause of mysterious deaths and illness that struck scores of Alaska seals last year, federal officials said on Friday.
Preliminary tests of tissue samples from animals that fell victim to the lesion-causing disease found that radiation levels were normal and within "the typical background range for Alaska," The National Oceanic and Atmospheric Administration said in a statement.
More than 60 dead and 75 sickened seals, most of them ringed seals, were found on the northern and western coasts of Alaska last summer and fall. Some walruses were also afflicted by the disease, with a smaller number found dead.
The affected animals have bleeding lesions on their flippers and other body parts, patchy loss of hair, labored breathing and lethargy, according to NOAA, which in December declared the problem an "unusual mortality event."
The findings that appear to clear the Fukushima plant of blame are only preliminary, Juneau-based NOAA spokeswoman Julie Speegle said, and more analysis will be conducted. Tests on healthy animals also found normal levels of radiation.
"Part of the reason it doesn't rule it out is we need to do more in-depth tests for Cesium 137 and Cesium 134," Speegle said.
An international team of scientists continues to investigate the outbreak, she said. Among possible causes being investigated are viruses, bacteria, biotoxins, or chemicals, she said.
There may be "something in the environment that's messing up the animals' immune systems," she said.
No sickened seals have been reported recently to NOAA, Speegle said. "We've had reports from hunters of healthy animals," she said. "We're hoping spring doesn't bring a new outbreak."
(Editing by Dan Whitcomb and Cynthia Johnston)